Known bicycle wheels comprise a plurality of spokes extending between the hub, which constitutes the central element of the wheel intended to be associated with the bicycle frame, and the rim on which the tire is mounted.
The hub, in turn, comprises a body on which the spokes and a shaft are intended to be mounted and a shaft, integrally and rotatably associated through bearings with said body and extending longitudinally inside of it, intended to be connected through its free ends to the bicycle frame.
An example of a hub known in the art and particularly advantageous in terms of practicality and simplicity of assembly of the spokes has a hub for flat spokes, in which the hub body comprises a tubular end portion terminating with an annular front surface having a plurality of radial front recesses constituting spoke housing seats. Each spoke has a widened head of attachment to the hub having a T-shaped configuration. Each spoke also has a flattened spoke body portion immediately adjacent to the widened head. The widened head of attachment to the hub is housed inside the tubular end portion of the hub body, whereas the flat portion of the body of the spoke is housed in the recess formed on the front annular surface of the hub body. The T-shape of the widened head of attachment to the hub prevents the spoke from moving in the radial direction of the wheel towards the rim once the spoke has been tightened. The movements of the spoke in the axial direction of the hub, towards the outside thereof, on the other hand, are prevented by an annular edge formed at the free end of the hub and bent radially inwards; such an edge extends circumferentially between each pair of contiguous recesses and defines an abutment surface for an upper portion of the front surface of the widened head of attachment to the hub of each spoke. Such an edge also defines on the recess an opening of a size equal to the width of the flat spoke body portion.
The Applicant has found that a hub of the type described above has the drawback that, following untightening or breaking of a spoke that causes a movement of the spoke in the radial direction of the wheel towards the centre of the hub (that is a movement of the spoke along its longitudinal axis towards the centre of the hub), the spoke can come out from the front recess in which it is housed and thus move away from the hub, thus compromising the correct operation of the wheel and/or constituting a danger to the cyclists, especially during a race where cyclists ride in groups.